Percussion fuse for projectiles



Aug. 27, 1929.

A. VARAUD PERCUSSION FUSE FOR PROJECTILES Filed May 16, 1928 3 Sheets-Sheet l Aug. 27, 1929. VARAUD PERCUSSION FUSE FOR PROJECTILES Filed May 16, 1928 3 Sheets-Sheet 0 7 H m 2 2 8 M m M 3 4 4 2 6 v 0 6 Q I 4 4: V

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Aug. 27, 1929. V D 1,726,325

PERCUSSION FUSE FOR PROJECTILES Filed May 16, 1928 3 Sheets-Sheet 3 9 u l0 F/0.13.

Patented Aug. 27, 1929.

PATNT FFHCE.

ANDRE VARAUD, OF GENEVA, SWITZERLAND.

PERCUSSION FUSE FOR PROJECTILES.

Application filed May 16, 1928, Serial No. 278,104, and in Switzerland July 19, 1927.

This invention concerns improvements in percussion fuses for projectiles of the kind having a relatively movable percussion pin and primer-carrying member, functioning under the action of inertia, mounted so as to be axially movable within the fuse and normally held apart by centrifugal means, themselves normally locked in operative position by inertia-operated members.

Such fuses have been provided with various means, either an antagonistic spring or a pin perpendicularly traversing the percussion pin and the body of the fuse, to prevent untimely action of thepercussion pin on the 1 primer due to the resistance of the air acting on the ppint of the projectile during its trajectory. It is true that there is thus obtained a certain safety of action, but this only at the expense of the sentsitiveness of thefuse held at a certain distance from the primer (up to 3 to 4 millimetres) which removes a,

large part of the instantaneous action on impact if the obstacle encountered by the point of the projectile is of weak consistency.

The percussion device (movable slide and striker), even when lightened as much as possible or made of material of a low density such as aluminium or electrum, weighs several grammes and thus possesses large momentum and energy. For a given force, the reaction rearwardly towards the primer is verysmall if the obstacle encountered is of feeble consistency.

In this case, the stoppage of the striker not being suificiently rapid, the time taken to traverse the space separating it from the primer reduces the effect of the burst, since I the projectile only bursts when it has already buried itself for some distance. The instantaneous bursting action desired is thus not obtained, from which results the ineflicacy of this kind of device.

It would appear that, to solve these problems and provide sensitive or instantaneousaction fuses, there could be provided a construction in which the spring between the primer and striker is weakened as much as possible, even below the force necessary to counterbalance the pressure of the air on the since at the impact the percussion pin has" strikerpin, means being provided to permit progressive movement of the striker towards the primer during the trajectory only after the projectile has traversed a certain part of its trajectory. It is, however, known that at the discharge the projectile is subjected to violent oscillations which may cause premature bursting if the fuse is made as sensitive as possible in the manner described.

It will be seen, on the other hand, that when the projectile has reached steady flight after a certain part of the trajectory is completed, the risk of premature bursting maybe obviated even with a sensitive fuse if the progressive movement of the striker towards the primer is caused solely at this time.

The object of the present invention is to provide a fuse of the kind in question having great sensitiveness but also being safe in" use; For this purpose there is provided a centrifugal member having rack teeth held engaged until the moment of firing between the striker and primer, in such manner as to prevent untimely movement thereof but to permit during the trajectory progressive movement of the striker towards the primer. The toothed centrifugal member meshes to that and with a wheel train of which the last ample, two forms of construction of the device according to the invention.

Fig. 1 is an axial section of the first form of construction in the position for transport,

- a tight hood and protective sleeve being provided.

Fig. 2 is a transverse section on the line AA Fig. 1. v

Fig. 3 is an axial section of this construction in the position for transport showing the train of wheels.

Fig. 4 is a plan of the body of the fuse, the head being removed to show the arrangement within thisbody.

Fig. 5 is an axial section of the same construction showing the position of the parts on the departure of the shell during the acceleration. the hood and protector being removed.

Fig. 6 is also an axial section, showing the fuse on impact.

Fig. 7 is an axial section of the second construction in position for transport and having a protective sleeve.

Figs. 8 to 10 are axial sections similar to F ig..7 showing the fuse on the departure of the shell, during the. trajectory andon the moment of contact of the striker on the primer at impact. a

Fig. 11 is a transverse section on the line AA of Fig. 7.

Fig. 12 is a plan of the body of the fuse, the head being removed to show the parts detachably mounted in this body.

Fig. 13 is a detail sectional view on axes of the clockwork wheels.

Figs. 14 to 16 are respectively an axial section, a partial elevation and a plan of a modification, the head being removed.

Referring to Figs. 1 to 12, it will be seen that the striker 1 is mounted so as to be axially movable in the percussion-control guide 2, which is itself axially movable in the head 3 of the fuse.

This mounting of the striker is adopted to prevent the impulse received, when shocks are produced during handling of the shell either directly or indirectly by inertia, from being transmitted to the striker from the guide 2. To that end a damping spring 4 is housed in the front of the guide 2 so as to bear on a shoulder 5 on the striker and on a plug 6 screwed into the end of the guide. This spring is of a size and diameter such as to offer a sufiiciently large resistance (about 14. to 15 kgs) to compression so as to absorb shocks on the point of the guide 2 either during handling orby inertia on the departure of the shell if, for example, firing is effected in a Wood and the point strikes the branch of a tree.

The striker 1 and the inertia plug 26 are held spaced from the primer 7 during transport and on the departure of the projectile by a-radial bolt 8 having rack teeth referred to hereinafter. This bolt has a central longitudinal slot 9 traversed perpendicularly by the point 10 of the striker 1, which normally rests by its shoulder on the bolt 8 as shown in Figs. 1 and 7.

The forked extremity of the bolt is bevelled at 11 so as to allow the striker to move propressively and gradually towards the primer, when the bolt is retracted under the action of centrifugal force. The bolt 8 is maintained in the operative position during transport by an inertia pin 12 (Fig. 11) of known form having claws or a spring and provided with a portion engageable in a corresponding transverse hole in the bolt. 1

Asthe inertia pin 12 might be retracted at the small accelerations it is necessary to provide means for holding said pin for safety in trans; port so that it is kept in operative position until the moment of firing, such as by means of a pin 19 engaged in an axial hole in the bolt 8 and fixed by means of a plug 22 (Figs. 7 to 16).

The rack teeth out on the bolt 8 control a train of wheels 13 housed in the body 14 of the fuse by means of a pinion 15 (Figs. 1 to 4 and 11 to 13). The last movable member of the train 13 is an escapement wheel 16 which co-operates with an anchor 17 oscillable about a pivotal axis eccentric-with respect to the axisof the projectile (Figs. 4 and 12). This anchor is slightly out of equilibrium (Fig. 12) so; that one of its arms is pushed,

under the action of centrifugal force, on the teeth of the escapement wheel 16 in such manner that the braking of this latter is proportional to the centrifugal force, in accordance with the speed of rotation of the projectile. The important part played by this anchor placed out of equilibrium by its eccentric mounting will thus be evident.

Experiments have shown that, due to this peculiarity of the anchor, the interval between firing and the moment at which the striker contacts with the primer is substantially the same in these fuses notwithstanding variations of initial speeds between 250 and 500 metres and of rotational speeds between 6,500 and 15,000 revolutions per minute, thus proving the efiicacy of the braking which is in fact proportional to the speed of rotation ofthe projectile.

The housing enclosing the train of wheels 13 and the escapement arrangement 16, 17 is in two parts 23, 24 detachably mounted in the body 14 (Figs. 12 and 13).

The functioning of this fuse is as follows:

At the moment of firing, the members 18, 19 in the first form (Figs. 1 to 6) and in the second form (Figs. 7 to 16) the pin 19 is first removed. the fuse being then ready for use. On the departure of the shell (Figs. 5 and 8) the guide 2 descends under the action of inertia on to the plate 20, screwed in the head 3, compressing the spring 4. Vhen the linear "acceleration ceases, the guide 2 reascends under the action of the spring 4 into the position shown in Figs. 1 and 7 whilst the bolt 8; under the effect of centrifugal force, commences to drive the pinion 15 and out of reach of the primer.

The escapement device 16, 17 then acts as a brake to slow down the radial displacement of the bolt 8 to allow the shell to travel a sufficient distance prior to the striker coming into contact with the primer or detonator.

When the slope 11 of the bolt 8 arrives against the shoulder of the striker 1 the latter, due to the air resistance acting on the guide 2, moves gradually towards the primer the train 13 while maintaining the striker 1 7 until it finally rests thereon, as in Fig. 9. The fuse is then ready to function at the occurence of the slightest impact.

A weak spring 21 is interposed between the slide 2 and the lower part 14 of the body or the plate 23 so as partially to counterbalance the action of the air on the slide 2, thus obviating any risk of the primer being perforated due to the air pressure.

Due to this contact of the striker point on the primer, there is obtained a very sensitive action but the use 'of the spring 21 prevents any premature action of the primer, it being understood that a relatively large force is required to cause perforation thereof. The prin'ier-carrying plug 26 operates by inertia in well-known manner.

It may be advisable in some cases with a view to ensuring bursting when the angle of the shell-trajectory is small or on slopes (which, as is known, are liable to cause misfire) for the fuses not to embody such inertiaoperated means.

Figs. 14 to 16 show a modification in which the spring 4 and inertia plug 26 are omitted and in which the pin 19, instead of having a loop for removal, is rovided with a tongue 25 fitting in or wel ed (soldered) into a corresponding groove in the body 14 having a loop for pulling off at the moment of firing.

What I claim is:

1. A percussion fuse for projectiles comprising in combination a striker, a primer, a housing in which said striker and primer are mounted so as to be movable relatively one to the other, a radial bolt-member normally separating said striker and primer but being slidably mounted in said housing to allow contact thereof during the flight of the projectile, an escapement device driven from and braking the movement of said bolt, said escapement being eccentrically positioned with regard to the fuse axis, and means for preventing movement of said bolt until the departure of the projectile.

2. A percussion fuse for projectiles comprising in combination a striker, a primer, a housing. in which said striker and primer are mounted so as to be movable relatively one to the other a guide in said housing for said striker, a first spring bein interposed between said striker and gui e, a second spring between the housing and the guide, a radial bolt-member normally separating said striker and primer but being slidably mounted in said housing to allow contact thereof during the flight of'the projectile, an escapement device driven from and braking the movementof said bolt, said escapement being eccentrically positioned with regardto the fuse axis, and means for preventing movement of said bolt until the departure of the projectile.

3. A percussion fuse for projectiles. comprising in combination a striker, a primer, a housing in which said striker and primer are mounted so as to be movable relatively one to the other, a radial bolt-member normally separating said striker and primer, but being slidably mounted in said housing to allow, contact thereof during the flight of the projectile, an escapement device driven from and braking the movement of said bolt, said escapement being eccentrically positioned with regard to the fuse axis, and comprising an anchor and toothed escapement, said anchor being out of equilibrium, and means for preventing movement of said bolt until the departure of the projectile.

4. A percussion fuse for projectiles comprising in combination a striker, a primer, :1. housing in which said striker and primer are mounted so as to be movable relatively one to the other, a guide in said housing for said striker, a first spring being interposed between said striker and guide, a secondv spring between the housing and the guide, a radial bolt-member normally separating said striker and primer but being slidably mounted in said housing to allow contact thereof during the flight of the projectile, an escapement device driven from and brakingthe movement of said bolt, said escapement being eccentrically positioned with regard to the fuse axis, and comprising an anchor and toothed escapement, said anchor being out of equilibrium, and means for preventing movement of said bolt until the departure of the projectile.

5. A percussion fuse for projectiles comrising in combination a striker, a primer, a housing in which said striker and primer are mounted so as to be movable relatively one to the other, a radial bolt-member normally separating said striker and primer but being slidably mounted in said housing to allow contact thereof during the flight of the projectile, said bolt having a forked and bevelled end in which the striker engages, an escapement device driven from and braking the movement of said bolt, said escapement being eccentrically positioned with regard to the fuse axis, and means for preventing movement of said bolt until the departure of the projectile.

l 6. A percussion fuse for projectiles comprising in combination a striker, a primer, a housing in which said striker and primer are mounted so as to be movable relatively one to the other, a radial bolt-member normally separating said striker and primer but being slidably mounted in said housing to allow contact thereof during the flight of the projectile, said bolt having a forked and bevelled end in which the striker enga es, an escapement device driven from and braking the movement of said bolt, said escapement being eccentrically positioned with regard to the fuse axis, and comprising an anchor and toothed escapement, said anchor being out of equilibrium, and means for preventing movement of said bolt until the departure of the projectile.

7. A percussion fuse for projectiles comprising in combination a striker, a primer, a housing in which said striker and primer are mounted so as to be movable relatively one to the other, a guide in said housing for said striker, a first spring between the striker and guide, a second spring between the housing and the guide, a radial bolt-member normally separating said striker and primer but being slidably mounted in said housing to allow contact thereof during the flight of the projectile, said bolt having a forked and bevelled portion in which said striker engages, an escapement device driven from and braking the movement of said bolt, said escapement being eecentrically positioned with regard to the fuse axis and comprising an anchor and toothed escapment, said anchor being out of equilibrium, and means for preventing movement of said bolt until the eparture of the projectile.

8. A percussion fuse for projectiles comprising in combination a striker, a primer, a"

housing in which said striker and primer are mounted so as to be movable relatively one to the other; a guide in said housing for said striker, a first spring being interposed between'said striker and guide, a second spring between the housing and the guide, a radialbolt-member normally separating said striker and primer but being slidably mounted in said housing to allow contact thereof during the flight of the projectile, said bolt having a forked and bevelled portion, in which said striker engages, an escapement device driven from and braking the movement of said bolt; said escapement being eccentrically positioned with regard to the fuse axis, and

amasas means for preventing movement of said bolt until the departure of the projectile.

9. A percussion fuse for projectiles comprising a relatively movable striker and primer, a radial bolt-member normally separating said members but being slidably mounted so as to allow-contact thereof after firing, a train of wheels driven on movement of said bolt to operate an escapement disposed eceentrically of the fuse axis, means for preventing movement of said bolt prior to firing and a housing in the fuse bodyfor said wheel train and escapement device.

'10. A percussion fuse for projectiles comprising a relatively movable striker and primer, a radial bolt member normally separating said members but being slidably mounted so as to allow contact thereof after firing, a train of wheels driven on movement of said bolt to operate an escapement disposed eecentr-ically of the fuse axis, said escapement comprisingan anchor and a toothed wheel driven-by said train of wheels, said anchor being out of equilibrium, means for preventing movement of said bolt prior to firing. and a.- housing in the fuse body for said wheel train and escapement device.

11. A percussion fuse for projectiles comprising a relatively movable striker and primer, a radial bolt-member normally separating said members but being slidably" mounted so as to allow contact thereof after firing, said bolt having a forked and bevelled portion in which said striker engages, a train of wheels driven on movement of said bolt to operate an escapement disposed eccentrically of the fuse axis, means for preventing movement of said bolt prior to firing, and a housing in the fuse body for said wheel train and escapement device.

In testimony whereof I have signed my name to this specification.

ANDRE VARAUD. 

